Lethal Dose Of Pentobarbital Research Articles

Measuring temporal expression, systematic response, and post-mortem stability to assess potential markers for estimating wound age: an example of Fosl1 in contused skeletal muscle

To assess whether Fosl1 is a suitable parameter for wound age estimation, a total of 126 male Sprague–Dawley rats were divided into control (n = 6 per group), contusion (including 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, and 48 h post-severe injury, and 4 or 8 h post-moderate or -mild injury subgroups), and post-mortem (including 6, 12, 18, and 24 h subgroups) groups (n = 6 per subgroup). A contusion was produced in the right limb of the rats using the drop-ball technique (under intraperitoneal chloral hydrate anaesthesia), and the animals were sacrificed using a lethal dose of pentobarbital. The expression of Fosl1 mRNA and protein was determined in the contused and contralateral uninjured muscle and post-mortem specimens of musculi quadriceps femoris using real-time PCR and western blotting, respectively. Compared with the control group, the expression of Fosl1 mRNA was increased in several contused and contralateral uninjured muscles, and decreased in post-mortem groups (P<0.05). The expression of Fosl1 protein was increased in the 4, 8, 32, 36, 40, 44, and 48 h contusion subgroups (P<0.05), but there was no significant change in the contralateral uninjured muscles and post-mortem specimens. The results indicated that Fosl1 protein was more specific and stable than Fosl1 mRNA, which suggests that the temporal expression, systematic response, and post-mortem stability should be comprehensively analysed when exploring other markers for use in wound age estimation in the future.

An “up, no change, or down” system: Time-dependent expression of mRNAs in contused skeletal muscle of rats used for wound age estimation

The combined use of multiple markers is considered a promising strategy in estimating the age of wounds. We sought to develop an “up, no change, or down” system and to explore how to combine and use various parameters. In total, 78 Sprague Dawley rats were divided randomly into a control group and contusion groups of 4-, 8-, 12-, 16-, 20-, 24-, 28-, 32-, 36-, 40-, 44-, and 48-h post-injury (n=6 per group). A contusion was produced in the right limb of the rats under diethyl ether anesthesia by a drop-ball technique; the animals were sacrificed at certain time points thereafter, using a lethal dose of pentobarbital. Levels of PUM2, TAB2, GJC1, and CHRNA1 mRNAs were detected in contused muscle using real-time PCR. An up, no change, or down system was developed with the relative quantities of the four mRNAs recorded as black, dark gray, or light gray boxes, representing up-, no change, or down-regulation of the gene of interest during wound repair. The four transcripts were combined and used as a marker cluster for color model analysis of each contusion group. Levels of PUM2, TAB2, and GJC1 mRNAs decreased, whereas that of CHRNA1 increased in wound repair (P<0.05). The up, no change, or down system was adequate to distinguish most time groups with the color model. Thus, the proposed up, no change, or down system provide the means to determine the minimal periods of early wounds.

Facilitated Diagnosis of Pneumothoraces in Newborn Mice Using X-ray Dark-Field Radiography

The aim of this study was to evaluate the diagnostic value of x-ray dark-field imaging in projection radiography-based depiction of pneumothoraces in the neonatal murine lung, a potentially life-threatening medical condition that requires a timely and correct diagnosis. By the use of a unique preclinical model, 7-day-old C57Bl/6N mice received mechanical ventilation for 2 or 8 hours with oxygen-rich gas (FIO2 = 0.4; n = 24). Unventilated mice either spontaneously breathed oxygen-rich gas (FIO2 = 0.4) for 2 or 8 hours or room air (n = 22). At the end of the experiment, lungs were inflated with a standardized volume of air after a lethal dose of pentobarbital was administered to the pups. All lungs were imaged with a prototype grating-based small-animal scanner to acquire x-ray transmission and dark-field radiographs. Image contrast between the air-filled pleural space and lung tissue was quantified for both transmission and dark-field radiograms. After the independent expert's assessment, 2 blinded readers evaluated all dark-field and transmission images for the presence or absence of pneumothoraces. Contrast ratios, diagnostic accuracy, as well as reader's confidence and interreader agreement were recorded for both imaging modalities. Evaluation of both x-ray transmission and dark-field radiographs by independent experts revealed the development of a total of 10 pneumothoraces in 8 mice. Here, the contrast ratio between the air-filled pleural space of the pneumothoraces and the lung tissue was significantly higher in the dark field (8.4 ± 3.5) when compared with the transmission images (5.1 ± 2.8; P < 0.05). Accordingly, the readers' diagnostic confidence for the diagnosis of pneumothoraces was significantly higher for dark-field compared with transmission images (P = 0.001). Interreader agreement improved from moderate for the analysis of transmission images alone (κ = 0.41) to very good when analyzing dark-field images alone (κ = 0.90) or in combination with transmission images (κ = 0.88). Diagnostic accuracy significantly improved for the analysis of dark-field images alone (P = 0.04) or in combination with transmission images (P = 0.02), compared with the analysis of transmission radiographs only. The significant improvement in contrast ratios between lung parenchyma and free air in the dark-field images allows the facilitated detection of pneumothoraces in the newborn mouse. These preclinical experiments indicate the potential of the technique for future clinical applications.

Comparison of the homogeneity of mRNAs encoding SFRP5, FZD4, and Fosl1 in post-injury intervals: Subcellular localization of markers may influence wound age estimation

The inter-group heterogeneity and intra-group homogeneity of relative expression are very necessary when the mRNA were used to determine wound age accurately in forensic medicine. The aim of this study was to assess the intra-group homogeneity of SFRP5, FZD4 and Fosl1 mRNAs in post-injury intervals. The corresponding proteins show different subcellular locations. A total of 78 Sprague–Dawley rats were divided into control and contusion groups. At 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, or 48 h (n = 6 per group) after contusion (under anesthesia by chloral hydrate intraperitoneally), the rats were sacrificed using a lethal dose of pentobarbital, and samples of the injured muscles were collected. The raw Ct values of SFRP5, FZD4, and Fosl1 mRNAs were obtained using real-time PCR. After normalized to RPL13 mRNA levels, the coefficient of variation (CV) and the relative average deviation (d%) of each normalized Ct, and their relative expression levels, were calculated in each post-injury interval. Two methods were applied to compare the homogeneity of the three genes. First, each gene was given a score based on its CV value in each post-injury interval. Then, the sum of the 13 scores was calculated; a low sum indicated high homogeneity. Second, the 13 calculated CVs or d%s were used as raw data, which was described as the mean ± SD. Based on this mean ± SD, a CV of the CVs and a d% of the d%s were calculated to represent the variation; a low value indicated high homogeneity. The sum of the variability of FZD4 mRNA was lower than those of the SFRP5 and Fosl1 mRNAs, consistent with the results that the FZD4 mRNA had the lowest mean, the smallest CV of all CVs, and the smallest d% of all d%s, among the three genes. In conclusion, these data indicated that mRNA encoding membranous FZD4 was likely to be more homogeneous than those encoding SFRP5 and Fosl1 within post-injury intervals.

Time-dependent expression of SNAT2 mRNA in the contused skeletal muscle of rats: a possible marker for wound age estimation

To estimate the age of skeletal muscle contusion, the expression of SNAT2 mRNA in contused skeletal muscle of rats was detected by real-time polymerase chain reaction (PCR). In total, 78 Sprague-Dawley male rats were divided into control and contusion groups. At 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, and 48h (n=6) after contusion, the rats were sacrificed with a lethal dose of pentobarbital. Another 24 rats received contusion injuries at 6, 12, 18, and 24h (n=6) after death. Total RNA was isolated from muscle specimens using the TRIzol reagent and reverse-transcribed into first-strand cDNA. Sequence-specific primers and TaqMan fluorogenic probes for SNAT2 mRNA and RPL13 mRNA were designed using the AlleleID6 software, and the expression levels of SNAT2 mRNA were determined by real-time PCR. At 4, 16, 20, and 24h after contusion, expression levels of SNAT2 mRNA normalized to RPL13 mRNA increased by 2.07 (P<0.05), 2.53 (P<0.05), 2.68 (P<0.05), and 2.06 fold (P<0.05) respectively, versus that in the control group. However, there was no significant change in the expression level of SNAT2 mRNA from 24 to 48h (P>0.05) after contusion, when normalized to RPL13 mRNA. There was no change in the expression level of SNAT2 mRNA between the normal skeletal muscle from the left limb of the same injured rat and the control. Also, no degradation of SNAT2 mRNA was detected in the postmortem samples (P>0.05). This result suggests that the determination of SNAT2 mRNA levels by real-time PCR may be useful for estimating wound age.

815 MOLECULAR STUDY OF PTEN AND SMAD4 GENES ON UROGENITAL SYSTEM OF THE RATS IN DIFFERENT AGES

You have accessJournal of UrologySexual Function/Dysfunction/Andrology: Basic Research (I)1 Apr 2013815 MOLECULAR STUDY OF PTEN AND SMAD4 GENES ON UROGENITAL SYSTEM OF THE RATS IN DIFFERENT AGES Beatriz Rocha, Sicília Colli, Leilane Nepomuceno, Diogo Souza, Bianca Gregório, Carla Gallo, and Francisco Sampaio Beatriz RochaBeatriz Rocha Rio de Janeiro, Brazil More articles by this author , Sicília ColliSicília Colli Rio de Janeiro, Brazil More articles by this author , Leilane NepomucenoLeilane Nepomuceno Rio de Janeiro, Brazil More articles by this author , Diogo SouzaDiogo Souza Rio de Janeiro, Brazil More articles by this author , Bianca GregórioBianca Gregório Rio de Janeiro, Brazil More articles by this author , Carla GalloCarla Gallo Rio de Janeiro, Brazil More articles by this author , and Francisco SampaioFrancisco Sampaio Rio de Janeiro, Brazil More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.381AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Cancer is increasing in low- and middle-income countries and it is a major public health problem in many parts of the world. Genes PTEN and Smad4 are involved in many cellular processes such as cell proliferation, migration, cell survival and apoptosis. Levels of Smad4 are increased in Gleason score 3-4 and are reduced in proportion to the increase of Gleason score. Recent studies showed that the combination of PTEN and Smad4 genes resulted in a high efficiency as a predictive tool of patient survival. We aimed to identify the expression of PTEN and Smad4 upon urogenital system organs of Wistar rats at different ages. METHODS The study was approved by the animal care and use committee of the Local Biology Institute (021/2012). Males and females wistar rats were separated into 3 groups, according to the age group corresponding: 21days (males, n=10 and females, n=5), 50 days (males, n= 5 and females, n=5) and 90 days (males, n=10 and females, n=5). All animals were killed with a lethal dose of pentobarbital. Bladder (males and females), ventral prostate, testis, ovary and uterus were removed and stored at −80°C for RNA extraction. Total RNA from tissue was extracted using trizol reagent, then 1 ug RNA was reverse transcribed by Superscript III to obtain cDNA. cDNA was used to evaluate the gene expression of PTEN and Smad4 by real time PCR using SYBR GreenER. The reactions were normalized by β-actin gene expression. Data were analyzed by one-way ANOVA and Bonferroni post-test, considering p<0.05. RESULTS Concerning PTEN gene expression in different ages no difference was found on bladder and prostate in male rats. On the other hand, the group of 90 days showed an increase of 80% in its expression on testis when compared to the 21 days group (p = 0.02). In different ages of females, PTEN gene expression did not vary on bladder and ovaries. As for gene expression of Smad4 in males, there were no differences in prostate and bladder among the groups. However, its expression was reduced on testis at 50 and 90 days (93% and 83%, respectively) when compared to the 21 days (p = 0.0005). As for females, the gene expression of Smad4 in bladder did not differ among different ages. Concerning ovary, the authors observed a reduction of 73% and 59% in its expression at 50 and 90 days, respectively, compared to the 21 days (p = 0.0030). CONCLUSIONS Thus, the increase in the expression of PTEN to 90 days can indicate a connection between the gender and its entry into puberty. Similarly, a reduction in the expression of Smad4 to 50 and 90 days seems to show an important role in the early development of the folicular and testicular development. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e335 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Beatriz Rocha Rio de Janeiro, Brazil More articles by this author Sicília Colli Rio de Janeiro, Brazil More articles by this author Leilane Nepomuceno Rio de Janeiro, Brazil More articles by this author Diogo Souza Rio de Janeiro, Brazil More articles by this author Bianca Gregório Rio de Janeiro, Brazil More articles by this author Carla Gallo Rio de Janeiro, Brazil More articles by this author Francisco Sampaio Rio de Janeiro, Brazil More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Curcumin Suppresses Soluble Tau Dimers and Corrects Molecular Chaperone, Synaptic, and Behavioral Deficits in Aged Human Tau Transgenic Mice

The mechanisms underlying Tau-related synaptic and cognitive deficits and the interrelationships between Tau species, their clearance pathways, and synaptic impairments remain poorly understood. To gain insight into these mechanisms, we examined these interrelationships in aged non-mutant genomic human Tau mice, with established Tau pathology and neuron loss. We also examined how these interrelationships changed with an intervention by feeding mice either a control diet or one containing the brain permeable beta-amyloid and Tau aggregate binding molecule curcumin. Transgene-dependent elevations in soluble and insoluble phospho-Tau monomer and soluble Tau dimers accompanied deficits in behavior, hippocampal excitatory synaptic markers, and molecular chaperones (heat shock proteins (HSPs)) involved in Tau degradation and microtubule stability. In human Tau mice but not control mice, HSP70, HSP70/HSP72, and HSP90 were reduced in membrane-enriched fractions but not in cytosolic fractions. The synaptic proteins PSD95 and NR2B were reduced in dendritic fields and redistributed into perikarya, corresponding to changes observed by immunoblot. Curcumin selectively suppressed levels of soluble Tau dimers, but not of insoluble and monomeric phospho-Tau, while correcting behavioral, synaptic, and HSP deficits. Treatment increased PSD95 co-immunoprecipitating with NR2B and, independent of transgene, increased HSPs implicated in Tau clearance. It elevated HSP90 and HSC70 without increasing HSP mRNAs; that is, without induction of the heat shock response. Instead curcumin differentially impacted HSP90 client kinases, reducing Fyn without reducing Akt. In summary, curcumin reduced soluble Tau and elevated HSPs involved in Tau clearance, showing that even after tangles have formed, Tau-dependent behavioral and synaptic deficits can be corrected.

Increased GABAA Receptor ε-Subunit Expression on Ventral Respiratory Column Neurons Protects Breathing during Pregnancy

GABAergic signaling is essential for proper respiratory function. Potentiation of this signaling with allosteric modulators such as anesthetics, barbiturates, and neurosteroids can lead to respiratory arrest. Paradoxically, pregnant animals continue to breathe normally despite nearly 100-fold increases in circulating neurosteroids. ε subunit-containing GABAARs are insensitive to positive allosteric modulation, thus we hypothesized that pregnant rats increase ε subunit-containing GABAAR expression on brainstem neurons of the ventral respiratory column (VRC). In vivo, pregnancy rendered respiratory motor output insensitive to otherwise lethal doses of pentobarbital, a barbiturate previously used to categorize the ε subunit. Using electrode array recordings in vitro, we demonstrated that putative respiratory neurons of the preBötzinger Complex (preBötC) were also rendered insensitive to the effects of pentobarbital during pregnancy, but unit activity in the VRC was rapidly inhibited by the GABAAR agonist, muscimol. VRC unit activity from virgin and post-partum females was potently inhibited by both pentobarbital and muscimol. Brainstem ε subunit mRNA and protein levels were increased in pregnant rats, and GABAAR ε subunit expression co-localized with a marker of rhythm generating neurons (neurokinin 1 receptors) in the preBötC. These data support the hypothesis that pregnancy renders respiratory motor output and respiratory neuron activity insensitive to barbiturates, most likely via increased ε subunit-containing GABAAR expression on respiratory rhythm-generating neurons. Increased ε subunit expression may be critical to preserve respiratory function (and life) despite increased neurosteroid levels during pregnancy.

Brain-Specific Deletion of Extracellular Signal-Regulated Kinase 2 Mitogen-Activated Protein Kinase Leads to Aberrant Cortical Collagen Deposition

The mitogen-activated protein kinases extracellular signal-regulated kinase (ERK)1 and 2 are essential intracellular mediators of numerous transmembrane signals. To investigate neural-specific functions of ERK2 in the brain, we used a Cre/lox strategy using Nestin:Cre to drive recombination in neural precursor cells. Nestin:Cre;ERK2(fl/fl) conditional knockout (cKO) mice have architecturally normal brains and no gross behavioral deficits. However, all cKO mice developed early-onset (postnatal day 35 to 40) frontal cortical astrogliosis, without evidence of neuronal degeneration. Frontoparietal cortical gray matter, but not underlying white matter, was found to contain abundant pericapillary and parenchymal reticulin fibrils, which were shown by immunohistochemistry to contain fibrillar collagens, including type I collagen. ERK1 general KO mice showed neither fibrils nor astrogliosis, indicating a specific role for ERK2 in the regulation of brain collagen. Collagen fibrils were also observed to a lesser extent in GFAP:Cre;ERK2(fl/fl) mice but not in CamKII-Cre;ERK2(fl/fl) mice (pyramidal neuron specific), consistent with a possible astroglial origin. Primary astroglial cultures from cKO mice expressed elevated fibrillar collagen levels, providing further evidence that the phenotype may be cell autonomous for astroglia. Unlike most other tissues, brain and spinal cord parenchyma do not normally contain fibrillar collagens, except in disease states. Determining mechanisms of ERK2-mediated collagen regulation may enable targeted suppression of glial scar formation in diverse neurological disorders.

Time-dependent expression of skeletal muscle troponin I mRNA in the contused skeletal muscle of rats: a possible marker for wound age estimation

To estimate the age of skeletal muscle contusion, the expression of troponin I mRNA in contused skeletal muscle of rats was detected using real-time polymerase chain reaction (PCR). A total of 51 Sprague-Dawley male rats were divided into control and contusion groups, and another nine rats received contusion injury after death. At 0.5, 1, 6, 12, 18, 24, 30, and 36 h after contusion, the rats were killed with a lethal dose of pentobarbital. Total RNA was isolated from muscle specimens using the SV Total RNA Isolation System and reverse transcribed into first-strand cDNA. Sequence-specific primers were then used to conduct real-time PCR to analyze the expression levels of sTnI mRNA. At 0.5, 1, and 6 h after contusion, the expression levels of sTnI mRNA decreased to 78.17% (P < 0.05), 41.58% (P < 0.05), and 32.13% of that in the control group, respectively. However, there were no significant changes in the expression levels of sTnI mRNA from 6 to 36 h (P > 0.05) after contusion when normalized to RpL32 expression. The expression levels of sTnI mRNA in the normal and contused skeletal muscle of postmortem rats were about 70% of that in the control group (P < 0.05), and no significant changes in the expression levels of sTnI mRNA in the postmortem contusion group were noted among different time points after injury. This result suggests that determination of sTnI mRNA levels by real-time PCR is useful for the estimation of wound age.

Are the toxicities of pentobarbital and ethanol mediated by the GABA-benzodiazepine receptor-chloride ionophore complex?

Both barbiturates and ethanol have been reported to interact with the GABA-benzodiazepine receptor-chloride ionophere ‘supramolecular complex’. These observations raise the possibility that some of the pharmacologic actions of barbiturates and ethanol may be mediated through this complex. In this study we have administered a series of drugs which bind to various components of the complex in an attempt to antagonize the lethality of sodium pentobarbital, and ethanol-induced loss of righting reflex in mice. It was found that isopropylbicyclophosphate (IPPO), a cage convulsant which binds at or near the chloride ionophore, greatly reduces the overall mortality (and increases latency to death) of animals pretreated with a lethal dose of pentobarbital. Picrotoxin also decreases pentobarbital lethality, but only at doses which were usually lethal when given alone. Picrotoxin shortened, rather than increased, latency to death. Strychnine did not prevent pentobarbital lethality, suggesting that the IPPO effect is not shared by convulsants in general. IPPO did not prevent ketamine-induced deaths, which supports the notion that the protective actions of IPPO are specific for depressant drugs which act at the chloride ionophore. IPPO also significantly reduced the duration of loss of righting reflex induced by ethanol. These observations suggest that the use of compounds which have a high affinity for the chloride ionophore in vitro might be fruitful in developing a clinical treatment for barbiturate or ethanol toxicity.

Central nervous system effects of hypothalamic peptides.

Intravenous (i.v.) administration of TRF (1 mg/kg) increases the LD50 of pentobarbital (PB) by 25% while the same dose of somatostatin results in a 30% reduction in PB LD50. A similar increase of PB LD50 by TRF was observed in hypophysectomized rats. Mortality was completely abolished in rats receiving TRF (1 mg/kg) ten minutes after a lethal dose of PB (120 mg/kg). Somatostatin (1 mg/kg) decreases strychnine-induced seizure duration and increases strychnine LD50 by 21% while TRF lowers the strychnine LD50 by 28%. These observations are consistent with central nervous system sites of action for TRF and somatostatin.

The action of activated charcoal on poisons in the digestive tract

Time course blood- or liver-drug analyses were performed to investigate the action of activated charcoal on poisons in the gastrointestinal tract. Blood was obtained from dogs treated orally with aspirin, pentobarbital, barbital, or glutethimide, and liver was obtained from rats treated orally with chloroquine, chlorpheniramine, or chlorpromazine. Test animals were treated with activated charcoal 1 min after drug administration. Control animals were given only the drugs. All the drug concentration curves of test animals were markedly lower than those of corresponding control animals. Semilogarithmic plots of the data suggest that dissociation of charcoal-drug complexes, if it does occur, is inconsequential. Administration of activated charcoal 1 min after poisoning is markedly more effective in reducing gastrointestinal absorption of drugs than the administration of charcoal 30 min after poisoning. Repeated administration of activated charcoal at 1- or 12-hr intervals, after an initial antidotal treatment, appears to exert no additional inhibition of gastrointestinal absorption of poisons. Activated charcoal, in a dose 5 times that of each poison, administered 30 min after poisoning, effectively reduced mortality in dogs given lethal doses of pentobarbital, barbital, or chloroquine. Intoxication developed so rapidly in some dogs that the administration of charcoal, 30 min after poisoning, was ineffective in preventing death. This investigation confirms the effectiveness of activated charcoal in the treatment of poisoning. It also emphasizes the need for immediate treatment with an adequate dose of the absorbent in the management of ingested poisons.

Short-term in situ perfusion of the canine kidney following death.

Experiments have been done to determine if isolated in situ perfusion of the cadaver kidney will preserve renal viability. Perfusion experiments were performed under varying conditions of time, pressure, renal blood flow, and temperature. The tetrazolium bromide dye reduction time, histology, and radioisotope renograms were all used as an index of kidney viability. <h3>Materials and Methods</h3> Isolated in situ perfusion of the kid[ill] neys was performed in 22 healthy mongrel dogs of both sexes weighing 15 to 30 kg (33 to 66 lb). Pentobarbital sodium was given intravenously in doses of 30 mg/kg for anesthesia. Immediately prior to perfusion each dog was killed with a lethal dose of pentobarbital. The pump perfusate was autologous whole blood obtained from the external jugular or femoral vein. It was oxygenated with a disposable Bentley oxygenator (oxygen [O₂] flow at 3 liters/min), and passed through a blood administration set filter. The oxygenated, diluted

Analeptic action of lysergic acid diethylamide (LSD-25) against pentobarbital.

Adventitious findings in this laboratory indicate that lysergic acid diethylamide (LSD-25) protects cats against the toxic effects of large doses of pentobarbital. One hundred forty cats have survived inordinate amounts of pentobarbital at the termination of experiments in which LSD-25 solution was given systemically. Gastaut,13Bradley,3,4and others6,8,14,18provide electrophysiological evidence that LSD-25 antagonizes the action of anesthetic doses of barbiturates. In these studies the actions of both drugs on the frontal cortex and on the reticular formation were investigated. There appear to be no reports, however, of the extent to which LSD might inhibit or reverse lethal effects of larger doses of barbiturates. It seemed worth while, therefore, to investigate in greater detail this protective property of LSD. Under the conditions of the present studies, LSD-25 safely and effectively reversed respiratory and central nervous system depression induced in cats by lethal doses of pentobarbital. What is